Could you describe how your skills developed? Like, first you felt like this, then eventually you felt like that... Sorry, vague question, I know.

But it's helpful for us newbies who currently see the path ahead as:

1) Year 1: Do aikido waza and ki-development exercises as relaxed and correctly as possible while listening to sensei, keeping in mind the 4 principles.
2) ??????...??
3) Year 10-20: You can now redirect force back to your attacker just by thinking about it with no apparent external movement.

I think you've pretty much nailed it there, your obviously on the right track.

As for the bounce demo that Michael and Mark are talking about I know Mike S. has talked to this one previously and as this is something that is developed in CMAs more than in aikido; he is obviously the authority here.

Having said that I don't think that this is something that is beyond the skills of those that have the ability to remain relaxed and stable at the same time.

I definitely think that the ability to focus past the point of conflict is one of the skills involved but focusing on what is happening with the body is also important. Otherwise how can you really teach/learn this?

What I think is happening within the body in this case is not that different to what is happening during any technique except that in this case the force of the attack is returned almost straight back at the uke.

I mean think about it for a minute what do you do in any irimi technique? Identify the soft spot in uke's attack and send your force there, right? Now if uke is expecting nage's body to move backward with the force of the push but meets an incoming force that is perhaps directed at their feet or hips, uke is likely to be jacked up in the air at which point nage can easily move uke backwards.

Looking at Shioda and Ueshiba when they do this, their ukes nearly always end up with the feet going forward while shoulders going back.

Now, if you can keep the shoulders soft to absorb the force of the attack allow this force to travel down and be stored in the hips and legs and fired back at uke from the hips, BAM, uke wont know what hit them.

Where those that can do this really well separate themselves from the chaff is when the movements become imperceptible and the uke just 'bounces'.

In short, I think the ability to maintain a relaxed structure (whilst absorbing pressure) and being able to fire off some power from the tanden back at the soft part of the push is what happens. Pure Irimi.